Gas flow regulators are used to provide a medical gas, such as oxygen, to a patient from a source supply of the gas. The gas is normally stored in a cylinder or supply vessel under high pressure. The gas flow regulator reduces the high pressure (about 500-3000 psi) to a lower pressure (about 50 p.s.i.) and provides the gas at a metered flow rate, measured in liters/minute. It is desirable to manufacture gas flow regulators as a compact, light weight and smooth to the touch package. It is also desirable to color code the devices to indicate the gas being handled (e.g., green for oxygen) or the preference of the owner of the device.
In the prior art, compact gas flow regulators are generally constructed in either a one-piece or two-piece aluminum alloy housing. In one-piece regulators, a pressure reducing element and flow control subassembly is typically held into the housing using a c-clip or snap ring. In these devices, the c-clips do not offer adequate stability. In addition, the flow control knob is usually snapped into place and can, therefore, accidentally separate from the regulator.
In two-piece regulators, a pressure reducing element and a piston are disposed within the yoke housing and a flow control housing, having a flow control element therein, screws together with the yoke housing. Consequently, the two-piece regulators have a characteristic division line between the yoke housing and the flow control housing. The use of two pieces also results in additional cosmetic problems. For example, it can be difficult to uniformly color the two housings due to variations in anodizing the pieces. Although two-piece regulators have a less desirable cosmetic appearance than one-piece regulators, the threaded attachment provides certain durability advantages.
In accordance with a preferred embodiment of the invention,a gas flow regulator combines the durability advantages of two-piece xe2x80x9cscrew togetherxe2x80x9d regulators with the cosmetic advantages of one-piece xe2x80x9cc-clipxe2x80x9d regulators. In particular, internal components are fabricated with a thread over their major diameter and are screwed into a yoke body which is fabricated to have a threaded minor diameter. The internal components are further secured in place by a fitting.
This combination of parts yields a one-piece regulator with improved durability and stability. In addition, the flow control knob is connected to the flow control body in such a way that the knob cannot separate from the regulator during use.
The modular system also permits the use of internal components which are fabricated from a different material than the yoke body. As such, the yoke body can be made from aluminum and the internal components can be made from brass. The resulting regulator can thus realize the advantageous of each material.
In accordance with an embodiment of the invention, a gas flow device includes an outer body with an inner cavity formed therein. The inner cavity is bounded by an inner wall of the outer body, the inner wall having a first coupling feature. An inner element, such as a pressure reducing element or a flow meter assembly, is disposed in the inner cavity. The inner element has an external wall with a second coupling feature. The inner element is secured within the inner cavity by mating the first and second coupling features.
The first and second coupling features can be matable threads. In addition, a fitting extends through the outer body and engages with the inner element to further secure the inner element within the outer body.
In accordance with another embodiment of the invention, a medical gas flow device provides gas at a selected flow rate from a pressurized supply tank. The device includes an outer body of a first material for physically connecting to the supply tank.
An inner core assembly is disposed within the outer body. The inner core assembly has an inlet for interfacing with gas from the supply tank and an outlet for outputting the gas at the selected flow rate. The gas traverses a gas flow path formed from a second material through the inner core assembly from the inlet to the outlet. In a particular embodiment, the outer body and the inner element or core assembly are of different materials. Specifically, the outer body is made of aluminum and the inner element is substantially made of brass.